Hypodermic syringes are well known to be used to deliver medication to patients. A traditional hypodermic syringe typically includes a syringe barrel having opposed proximal and distal ends. A cylindrical chamber wall extends between the ends and defines a fluid-receiving chamber. The proximal end of the traditional syringe barrel is substantially open and receives a plunger in sliding fluid-tight engagement. The distal end of the traditional syringe barrel includes a passage communicating with the chamber. A needle cannula is mounted to the distal end of the traditional syringe barrel such that the lumen of the needle cannula communicates with the passage in the chamber of the syringe barrel. Movement of the plunger in the proximal direction draws fluid through the lumen of the needle cannula and into the chamber. Movement of the plunger in a proximal to distal direction urges fluid from the chamber and through the lumen of the needle cannula.
The traditional syringe is designed for a variety of clinical operations. Many applications require needle changing or connection of the syringe to items such as stopcocks or tubing sets. Typically, traditional syringes create a dead-space between the connection of the syringe and the needle hub. These traditional syringes often trap and waste a certain amount of medication in the dead-space after injection. The amount of drug that is not expelled after injection and remains trapped in the fluid transfer connection is wasted when the syringe is discarded.
A typical traditional hypodermic syringe has three major components: (i) a syringe barrel; (ii) a plunger rod; and (iii) a stopper. Each of the three major components are described more completely below. As previously stated, hypodermic syringes contain a certain amount of dead-space between the connection of the syringe barrel and needle hub. This dead-space has been shown to cause waste of medication as well as added expense. The increase in cost is exacerbated when expensive drugs are delivered to the patient.
Attempts to reduce the dead-space between the syringe barrel and the needle hub in the traditional syringe are aggravated by the tight manufacturing tolerances of the mating components' dimensions required to minimize the dead-space. In addition, use of various syringe barrels and needle hubs from different manufacturers, which operate under different manufacturing tolerances of the above mating components' dimensions, can create an even more difficult situation to hold the dead space to a bare minimum.
Therefore, advancements in hypodermic syringes to reduce dead-space are still dependent on manufacturing tolerances of the mating components' dimensions. Thus, while some prior art hypodermic syringes attempt to reduce the dead-space and save medication costs, the dead-space still varies with the manufacturing tolerances of the mating components' dimensions. There is still a need for an improved fluid transfer connection between the syringe barrel and needle hub that will reduce the dead-space and remain independent of manufacturing tolerances of the mating components' dimensions.